Method of storing gases



Patented Dec. 22, 1953 2,663,626 yMETHOD OF STORING GASES Carl V. Spangler,

tion of Missouri Pittsburgh, Pa., Pritchard & Co., Kansas City, M

assigner to J. F.

o., a corpora- Application May 14, 1949, Serial No. 93,384

6 Claims.

This invention relates to a method of storing or stock piling of gases, for example, hydrocarbon gases such as propane, methane or natural gas such as the commercial pipe line gas which is now distributed on almost a nation-wide basis; the principal object being the practical, safe and economical storage of such gas through adsorption by a solid adsorbent material at relatively low pressures and at a temperature conveniently above liquefaction temperature of methane.

It is also an object of the invention to provide for release of the adsorbed gas when the gas is desired for use or to augment the low volume in a pipe line at times of high demand.

In accomplishing these and other objects of the invention hereinafter described, I have provided an improved method and apparatus which is diagrammatically illustrated in the accompanying drawing wherein:

l designates a pipe line leading from a supply of natural gas, for example, a commercial high pressure gas transportion system by which .natural gas is conveyed from a field of production to a market which may be many miles from the source of supply. Profitable operation of such systems depend upon substantially full pipe line Iiow. Consequently, during times of low demand for the gas, adequate storage must be profrom itV comprovision of a` The 'vessel may ducted through tainer M wherein the methane cools the adsorbbottom l1 and In carrying out the invention the gas to be stored is brought from the line t into the storage system through an orice meter indicated at 2 and passed through a purication plant 3 in which all traces of vapor phase moisture is removed from the gas together with any possible carbon dioxide, hydrogen sulde, or other acid gases which may be mixed in the main gas supply as impurities.

After puriiicationv the gas passes through a pipe 4 to a compressor 5 by which the gas is conducted through a pipe E to a heat exchanger 7 in which the gas is prechilled prior to discharge through a pipe 8 to a refrigerating apparatus 9. The refrigeration apparatus may be of any suitable type and utilize various methods of refrigeration depending upon theindividual situation. The temperature of the gas as it leaves the refrigeration system will be just above the liquefaction temperature of the methane at the operating pressure. I have determined that a practical operating temperature range isI from substantially C. to substantially -l47 C. The refrigerated gas is then conducted through a pipe IU to a separator Il wherein those materials which have been'liquefled or solidied are separated together with any liquid methane that may have formed inthe refrigeration process. The liquid so removed will be taken out through a pipe I2 to a separate outside storage system (not shown) and will not enter into any processing embodying the present invention, The vapor phase methane that is left in the system is chilled y almost to rliquefaction temperature and is cona pipe i3 to the adsorbentconentv bed and by continuous re-circulation eventually becomes an integral part of the solid adsorbent material by adsorption thereon.

'Ifhe storage constitutes a vessel l5 ofample capacity to contain the required amount of material to adsorb the volume of gas to be stored.

be of any suitable shape, for example, it may comprise a circular side wall i6, a

a top i8 constructed with substantially tight joints. to prevent directleakage into faces with an l vmaintain the desired low temperature of the and out of the vessel. The vessel is completely insulated preferably by lining all the interior surinsulating material l@ suflicient to methane. With this method of insulation, the walls of the vessel are protected from becoming friable and structurally unsafe at the extremely low temperatures involved, Therefore, special expensive alloys and construction are not" relation from abrasion by It quired as in cases where the metal is in direct contact with low temperatures. In fact, such tanxs as now used for large oil or gas storage might be used with modifications for handling the materials herein involved. lt is important, however, that the thickness and nature of the insulating material be selected as the best available for the duty. Suitable insulating materials are readily obtained which have adequate strength, thermal capacities and general physical and chemical qualications for the duty described. It is also desirable to select an insulation that is resistant to abrasion by the adsorbing material.

Such materials need only protection troni thev weather, which function is supplied by thev con tainer.

The gas from the separator is discharged Vinto the vessel through a duct distribution system which in the illustrated instance comprises a header 2i! which connects the inlet pipe with a plurality of distribution ducts 2l having perforations through which the gas is distributed subn 'stantially uniformly over the horizontal cross Vsectional area of the vessel.

. A similar collection system of per-forato ducts 22 is located under the roof insulation and connected by a header 23 with a discharge pipe 24. The header systems are iorroed of a suitable material to withstand the temperatures involved. Since the header systems are cooled by the gas passing therethrough, insulating seals 25 and 25 are required Where the pipes pass through the Walls of the vessel.

Filling the space Within the vessel is av body of solid adsorbent material 2l. The adsorbent material is allowed to rest directly on. the insulating material on the bottoni of the vessel and to hll out against the sides. 'In turn. the insulation across the top of the vessel and above the adsorbent material rests directly on the bed oiv adsorbent- In order to taire advantagevoi possible. physical characteristics of either insulation or adsorbent inaterial, structural props or supports might besupplied if needed to take or distribute sorne oi the stress.

In case an insulating material. is used requiring some support for the adsorbent, a thin sheet metal sheathing may be used to protect the insuthe solid adsorbent as a protection against physical damage during l-ling, construction or maintenance operations. Such sheathing would not be installed as a pressure vessel but is perforated to allow free passage of gas into the insulation so that the sheathing would not collapse under differential pressure during operation.

The adsorbent 21 may comprise one or a mixture of two or more of the Well-known adsorbent materials such as an adsorbent clay, attapulgite, iullers earth, activated bauxites, aluminas, calcium sulfate, silica or alumina gels, etc. These materials are all solidsy and may bep spared for use in av variety of ways.

lnoperation, the. adsorbent. material: is cooled by the methane gas entering the storage vessel and the methane is adapted to be adsorbed in progressively increasing amountby recycling the gas. Unadsorbed gas is discharged from the storage vessel through the discharge. system and is returned to the heat exchanger l through the pipe 2t for heat exchange with thev incoming gas to precool the incoming gas. The una-dsorbed gas after passing through the heat exchanger is discharged through a pipe 28 which connects with the pipe on the suction side of the compressor.

carbons and charcoals,

the nitrogen should be i The unadsorbed gas is thus mixed with the incoming gas and is recirculated through the system. Passage of the unadsorbed gas through the adsorbent bed reduces the temperature of the adsorbent 21 by removal oi sensible heat from the adsorbent bed and removal of latent heat of adsorption, the heat being carried away by the gas which is drawn o'i for recirculation through the refrigeration system. Progressively, the adsorbent material will gradually be chilled down to a temperature approaching the inlet methane teniperature. The lower the temperature of the adsorbent bed the more methane it will adsorb up to 'its "indicated maximum capacity.

When it becomes necessary and desirable to use the gas in storage, a Warm methane or natural Agas is circulated by the compressor 5 through the heat exchanger 'E and through the refrigeration 'apparatus S which nov: used as a heater to increase the temperature oi the cirnulated The refrigeration apparatus is converted to a heating system by circulating therethrough in heat exchange relation with the heat [rorn a source of supply indicated at which might be a steam boiler plant, the steam being irculated through the pipe connections 3l and Ei with the reirigerating coil. The heated gas is the-n passed through or around the separator column il (which now has no iunction) into and through. the adsorbent storage ced through the distribution duc*D 2l. On passing through the adsorbent bed the comparatively warm gas adds heat to it, raising the temperature thereof, adding sensible heat to the adsorbent, and furnishing the latent heat oi desorption for the methane adsorbate, thus sheeting its release as a free vapor or gas. The desorbed gas thus freed led out through the heat exchanger 'i and compressor 5 for release. through an orifice meter and delivery pipe 33 for repressuring the gas supply in a pipe line or for use as desired.

In. addition to storage oi methane, the invention involvesjseparation ci methane and/ or other hydrocarbons in naturalgas, from nitrogen which, as above stated, occurs in the natural gas in variable amounts from certain natural gas field sources. The nitrogen not being combustible and having no heat value decreases the B. t. u. value of the natural gas mixture on a volume basis. Therefore, nitrogen is usually and justly regarded as an undesirable dilutent or impurity. r.lo avoid the expense of handling the nitrogen through a pipe line transmission and distribution system,

removed.

I have foundthat nitrogen and methane as a natural gas mixture can be separated by means of the adsorbent bed when the gas mixture is passed through the bed oi solid adsorbent with both the mixture and the adsorbent bed at ternperatures just above the liqueiaction temperature of methane' at the contact pressure. Under these temperature conditions, the methane is adsorbed. on thev adsorbent as an adsorbate, but the nitrogen is adsorbed to a lesser extent as show-n in Example l hereinafter included' and the unadsorb'ed nitrogen passes through the adsorbent4 bed as a free gas. The ninogenv soireleased can then be disposed of as required under the operating conditions, if it has value.

After processing a methane-nitrogen natural gas mixture as described, the adsorbent eventually becomes saturated with the methane adsorbate, and no longer removes methane from the gas mixture under circulation.

no further The valuable methane adsorbate can be rei covered from the adsorbent when needed by circulating gas through the adsorbent bed at a temperature higher than the separation or adsorbing temperature in the same manner as previously described.

Attention is directed to the fact that it is pos`- sible and practical to desorb at a changed pressure than the adsorption pressure, thus altering the equilibrium to desorb at a more favorable temperature, however, under normal operating conditions desorption would be accomplished at adsorption pressure.

If the container of the adsorbent should rupture and the adsorbent spill out on the ground it will not flow as a liquid nor will the gas escape rapidly as a free gas. The adsorbent will merely accumulate in a pile as 'a solid at the location where it is spilled. On exposure to atmospheric temperatures, the methane will escape slowly as a gas from the pile of solid material. This is because the latent heat of desorption required to release the gas from the adsorbent as vapor must be obtained from the atmosphere or other source. This effect or flow of heat is retarded since the comparatively low temperature of the solid material causes the atmospheric moisture to con dense thereon as frost or ice,A thus insulating the material from further increase of temperature or heat input from atmosphere which slows clown escape or vaporization of the gas.

The results are given by the following examples:

Example 1 Results on the adsorption ci the adsorbate methane, on the adsorbent attapulgite (activated at 315 C., 30/09 mesh) Capacity of adsorbent for adsorbate methane, CE1, at 800 mm. Hg pressure Temperature in degrees Gentigrade 16.5 mL/gram. 340 nil/gram.

Capacity of adsorbent for adsorbate methane, CHl, at 800 mm. Hg pressure Temperature in degrees Centigrade 17.7 mL/gram.

M C n 335 mL/gram.

Example 3 Results on the adsorption oi the adsorbate methane, on the adsorbent bauxite (activated 1100" F. 2li/60 mesh) z Capacity ofadsorbent for adsorbate Temperature in degrees Centigrade pressure 12.0 mL/grorn.

Example 4 Comparison of results on the adsorption of methane 01H4 and nitrogen N2,

C. 30/60 mesh) Capacity oi odsorb ent for adsorbate at 800 mm. Hg pressure Temperature in degrees Centigradc Methane, +25 C 16.5 inl/gram.

It is to be emphasized that the drawing is schematic and has been made as simple as pos- -sible for illustrative purposes and it is obvious that various bypasses, automatic controls, valves, etc. are used to obtain the most advantageous heat balance and design consistent with economics, engineering, local gas pressures and tem'- peratures and other attendant local gas pressures and temperatures. Such additions, W- ever, will not change the principles of the invention as herein described. Y

From the foregoing it is obvious that I have provided a practical, safe and economical method vof storing methane or natural gas through adsorption by. a solid adsorbent material at relatively low pressures and temperature conveniently above the liquefaction temperature of methane. It is also obvious that the adsorbed gas is readily released for use Vwhen it is desired to augment the now volume in a pipe line at times ofhighdemand for gas.

While I have speciiically illustrated and described thc adaptation of my invention to the storage and stock piling of natural gas, it is obvious that other gases may be stored in like manner by maintaining temperature suitable for holding the gas as an adsorbate in an adsorbent material.

What I claim and desire Patent is:

1. The method of storing a high pressure natural gas on a solid adsorbent material and releasing the gas from storage when needed including cooling the gas to a temperature above the liquefaction temperature of the gas, bringing the cooled gas into contact with a solid adsorbent material to eiect adsorption of the gas on said maf terial, maintaining the adsorbent material at a temperature for holding theA adsorbed gas as an adsorbate in said material, heating the natural gas when storage gas is needed, passing the heated natural gas to the place of adsorption to release the adsorbed gas, and mixing the released gas with the heated natural gas.

2. The method of storing a high pressure natural gas on a solid adsorbent material including cooling the gas to a temperature above the liqueto secure by Letters faction temperature of the gas, bringing the cooled gas into contact With a solid adsorbent material to effect adsorption of the gas on said material, recirculating unadsorbed gas to the place of cooling, and returning the unadsorbed gas to the place of adsorption to maintain adsorbent at a temperature for holding the adsorbed gas as an adsorbate in said material.

3. The method of storing a high pressure natural gas on a solid adsorbent material including cooling the gas to a temperature above the liquefaction temperature of the gas, bringing the cooled gas into contact with a solid adsorbent material to effect adsorption of the gas on said material, removing unadsorbed gas from the place of adsorption, bringing the unadscrbed gas into heat exchange relation with incoming Warm gas,

misdng'said removed gas with Vthe incomingv gas, coolingv said mixture and.' passing. the cooled mixture into contact With the adsorbent material to effectadsorption of additional gas, and maintaining temperature oi the adsorbent material at the place of adsorption to hold the adsorbed gas as an adsorbate in said material.

4. The. method of separating and storingA a gas component of a mixed gas stream on a solid adsorbent material including cooling said gas stream `to a temperature above the lquefaction temperature of said component gas to be separated and stored, bringing the gas stream into contact with a solid adsorbent material to effect adsorption of said component gasY on said material, removing unadsorbed gas from the place of adsorption, bringing the unadsorbed gas into heat exchange relation with the incoming gas stream, mixing the unadsorbed gas with the incoming gas stream, cooling said mixture and passing the cooled mixture into contact With the adsorbent material to effect additional adsorption of said component, and maintaining temperature of the adsorbent material to hold the adsorbed component gas as an adsorbate in said material.

The method of separating and storing the methane content of natural gas on a solid adsorbent material including cooling the natural gas to atemperature just above the liquefaction temperature of the methane content of the gas at storage pressure, bringing the natural gas into contact with a solid adsorbent material to efect adsorption of the methane on said vmaterial, removing unadsorbed gas from the place of adsorption, bringing the unadsorbed gas into heat exchange relation with incoming warm naturalgas, mixing the unadsorbed gas with the incoming natural gas, cooling said mixture and passing the cooled mixture into contact with the adsorbent materialto effect adsorption of addii tional methana and maintaining temperature of the adsorbent material to hold the adsorbed methane as an adsorbate in said material at storage pressure.

6. The method of storing natural gas on a solid adsorbent material and releasing the natural gas from storage when needed for use including cooling the gas to a temperature just above the liquefaction temperature of the gas, bringing the gas into contact with a solid adsorbent material to effect adsorption of the gas on said material, recirculating unadsorbed gas to the place of cooling, returning the unadsorbed gas to the place of adsorption to maintain adsorbent at a temperature for holding the adsorbed gas as an adsorbate in said material while in storage, and heating the adsorbent material to release the adsorbed gas when the gas is needed for use.

CARL V. SPANGLER.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 879,129 Dewar Feb. 11, 1908 1,230,531 Stephenson June 19, 1917 2,535,148 Martin et al. Dec. 26, 1950 2,560,152 Berl July 10, 1951 2,575,519 Imhoff et al. Nov. 20, 1951 FOREIGN PATENTS Number Country Date 711,981 France July 8, 1931 OTHER REFERENCES Perry: Chemical Engineers' Handbook, 2nd ed., page 1318, New York, McGraw-Hill Book Co., 

1. THE METHOD OF STORING A HIGH PRESSURE NATURAL GAS ON A SOLID ADSORBENT MATERIAL AND RELEASING THE GAS FROM STORAGE WHEN NEEDED INCLUDING COOLING THE GAS TO A TEMPERATURE ABOVE THE LIQUEFACTION TEMPERATURE OF THE GAS, BRINGING THE COOLED GAS INTO CONTACT WITH A SOLID ADSORBENT MATERIAL TO EFFECT ADSORPTION OF THE GAS ON SAID MATERIAL, MAINTAINING THE ADSORBENT MATERIAL AT A TEMPERATURE FOR HOLDING THE ADSORBED GAS AS AN ADSORBATE IN SAID MATERIAL, HEATING THE NATURAL GAS WHEN STORAGE IS NEEDED, PASSING THE HEATED NATURAL GAS TO THE PLACE OF ADSORPTION TO 